kb/dns_failure.md

DNS Resolution Failure

Symptoms

• getaddrinfo ENOTFOUND or NameResolutionFailure
• Transient errors resolving service hostnames
• Works from one namespace/host but not another

Checks

• Resolve target host from pod/host (nslookup, dig)
• Inspect /etc/resolv.conf search domains and ndots
• Verify CoreDNS logs for SERVFAIL/REFUSED
• Check recent DNS changes or missing A/CNAME records
• Validate network policies allowing DNS traffic

Fix

• Correct service/record names and search domains
• Restart CoreDNS or propagate zone updates
• Add caching and lower ndots if needed
• Update network policies to allow UDP/TCP 53